Abstract: According to WHO classification. 54 cases of small cell carcinoma of thelung were hiatological subbtyped. of these, oat cell type 42 cases, intermediate celt sutype 7 cases, 5 cases of combined oat cell subtype. All the 54 cases were treatcd with the same Combinedion chemtherapy with or Mithout radiotherapy, for oat cell carcinoma, complete and partial response was 69%. for intermediate subtype and snixed cell subtype, only 50% had partial response. compared with intermediate cell and combined oat cell, oat cell carcanoma responce was sign ificantly higher (P1.01). 15 cases of oat cell carcinoma were observed with complete response, among them 6 cases were found to be long-term disease free for 3-10 years. on the fther bend, only one case observed of intermedate tand mixed cell subtype sureived 29 months For subtype oat cell carcinoma, the median survival rate was significantly higher than subtgpe intermediate and mixed oat cell carcinoma(12months SV 5 months, p0.01)